1. Field of the Invention
The present invention generally relates to the specification of interchange document indices that provide data processing systems the necessary information to construct application dependent indices to an object oriented document database for random object retrieval. Processes may select portions of a document to build locally optimized database indices from the interchange form of a stored library document without processing the entire document. The invention also enhances document sharing through the elimination of replicated forms of the library document that occur when application processes build "process local copies."
2. Description of the Prior Art
In data processing systems, there are the correlative problems of storing data in an efficient manner and later accessing the stored data, also in an efficient manner. The stored data constitutes a database the value of which is considerably enhanced when it may be shared by multiple "processes" at the same time. In this context, a process may be considered a computer application program, and it is assumed here that the computer application programs which may access the data in the database may be diverse programs; that is, the programs are not identical. This in turn assumes a certain protocol in the storing, accessing and interpreting the data in the database which is observed by all processes.
There exist various database system architectures which implement various data structures, including the relational approach, the hierarchical approach and the network approach. Generally speaking, the relational approach presents the database to a user as a series of tables. The hierarchical approach presents the user with a view of the database as a tree structure having a "root" and a plurality of branching "nodes". A node connected to another node that is closest to the root is described as the "parent" and the other, as the "child". The network approach has some similarity to the hierarchical approach in that data is represented as linked records.
The subject invention uses a hierarchical approach to database management and indices because it mirrors the hierarchical structure of a compound interchange document containing both architecture defined (e.g., a page) and user defined (e.g., a paragraph) document elements. The general concepts of and the use of indices are well known in the data processing arts, and it is assumed that those skilled in the art will be well versed in the same. Further background may be had by reference to the text book by Christopher J. Date entitled An Introduction to Database Systems, vol. 1, third edition, published 1981 by Addison-Wesley.
The specific environment of the invention is in the field of a data stream architecture that allows processing applications the capability to interchange document data from a sending application program to a receiving application program without knowing the receiver's processing capability. Normal work with an object oriented interchange document requires reading the entire file and building a "process local" document copy together with its own index. This requires excessive time and takes up storage which could be used for other purposes.